This invention relates to the field of water-air interactions, specifically the extraction of water from moist air (a mixture of air and water vapor).
Water, especially potable water, is a constant need. Obtaining water is a threshold requirement for most human and animal activity. Obtaining water can be especially problematic in arid areas. Tremendous effort and expense currently go to drilling wells, building water transport systems, and purifying and desalinating water.
Water is conventionally obtained by purifying existing liquid water. Reverse osmosis, distillation, and filtration are used to purify contaminated water. Desalination is used to produce potable water from sea water. These approaches can be energy-intensive, and require the presence of liquid water as the starting material.
If liquid water is not available, then purification processes are not applicable. Dehumidification by refrigeration can be used to produce liquid water from moist air. Conventional refrigeration processes are very energy-intensive, however. Further, conventional refrigeration processes can involve large and complex machines. Consequently, conventional refrigeration processes are generally not economical for production of potable water.
Accordingly, there is a need for a method and apparatus for obtaining potable water from moist air that does not require the expense or complexity of conventional refrigeration processes.
The present invention provides a method and apparatus for extracting liquid water from moist air using minimal energy input. The method can be considered as four phases: (1) adsorbing water from air into a desiccant, (2) isolating the water-laden desiccant from the air source, (3) desorbing water as vapor from the desiccant into a chamber, and (4) isolating the desiccant from the chamber, and compressing the vapor in the chamber to form liquid condensate. The liquid condensate can be removed for use. Careful design of the dead volumes and pressure balances can minimize the energy required. The dried air can be exchanged for fresh moist air and the process repeated.
The apparatus comprises a first chamber in fluid communication with a desiccant, and having ports to intake moist air and exhaust dried air. The apparatus also comprises a second chamber in fluid communication with the desiccant. The second chamber allows variable internal pressure, and has a port for removal of liquid condensate. Each chamber can be configured to be isolated or in communication with the desiccant. The first chamber can be configured to be isolated or in communication with a course of moist air. Various arrangements of valves, pistons, and chambers are described.
Advantages and novel features will become apparent to those skilled in the art upon examination of the following description or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.